The present invention relates in general to an electron beam scanning device, and more particularly to a flat tube display having internal structural supports.
Cathode ray tubes (CRT) used for display purposes in general are large volume devices housing structure for forming and deflecting and using an electron beam. Conventional television systems are bulky primarily because depth is necessary for an electron gun plus the associated deflection system.
Information systems generally, including television and alphanumerics, depend upon effective display of information which a viewer is to perceive. CRT devices are among the many types of systems used to present such data. CRT systems are more versatile than many other display devices in that they permit presentation not only of alphanumeric data, but also of full range analog data in black and white as well as in color.
There exists the need for a flat tube display, i.e., a tube in which the ratio of display area to enclosed volume is greatly minimized relative to existing devices. The idea would be a thin plate or panel on which there would appear such information as is designated by input digital or analog input signals.
Flat tube displays become increasingly difficult to build as they become larger because of the strength required in the face plate and the envelope to withstand atmospheric pressure. This problem is especially severe in a video display where the display is continuous and there is no room between display elements to attach the support structure. If internal supports could be incorporated in the flat tube display without interferring with the display itself, displays of any arbitrary size could be made using light weight face plates and envelopes.
One method of flat tube display construction having internal support is taught in U.S. Pat. No. 3,935,499, issued Jan. 27, 1976, assigned to Texas Instruments Incorporated, the same assignee of the present application. In the embodiment a plurality of ribs serve to support the face plate against atmospheric pressure so that evacuation of the interior of the envelope formed by the base and the face plate will not result in breakage of the relatively thin face plate. However, it is to be noted that a full screen presentation will not be possible because of the contact areas between the support structure and the face plate. For small diameter tubes only a mesh structure may be interdeposed between the face plate and the top of the support structure in order to prevent the dead areas on the screen.
In supporting the flat tube display by the internal ribs between the output buffer and the phosphor screen sufficient area must be provided between the apertures for atachment of the ribs. This construction imposes a limitation on the resolution achievable in the flat tube display when using the internal rib supports at the output buffer stage.
Accordingly, an object of the present invention is to provide an internally supported flat tube display where the support structure does not limit the resolution of the display.
Another object of the present invention is to provide for the fabrication of flat tube displays using light weight face plates and back plates independent of the display size.
Yet still another object of the present invention is to provide an internally supported flat tube display where the support structure does not reduce full screen presentation.